show 'read in browser' only for epubs

cps/templates/detail.html

@@ -78,7 +78,10 @@
             {% if g.user.kindle_mail %}
             <a href="{{url_for('send_to_kindle', book_id=entry.id)}}" id="sendbtn" class="btn btn-primary" role="button"><span class="glyphicon glyphicon-send"></span> Send to Kindle</a>
             {% endif %}
-            <a target="_blank" href="{{url_for('read_book', book_id=entry.id)}}" class="btn btn-primary" role="button"><span class="glyphicon glyphicon-eye-open"></span> Read in browser</a>
+            {% for format in entry.data if format.format|lower == 'epub' %}
+              <a target="_blank" href="{{url_for('read_book', book_id=entry.id)}}" class="btn btn-primary" role="button"><span class="glyphicon glyphicon-eye-open"></span> Read in browser</a>
+            {%endfor%}
+            
 
         </div> 
       </div>